Number of delegates needed to win the 1968 Republican nomination on the first ballot: 667
Number of delegates Nixon got in 1968 IOTL on the first ballot: 692
Number of delegates Goldwater got in 1964: 895
"All the top Goldwater plotters from 1964 were in the Nixon camp, even William F. Buckley, even Goldwater himself— all, that is, except F. Clifton White. All the Republican candidates had approached White to work for them. Nixon did it twice, the second time offering him the party chairmanship. “No thank you,” White replied, as Nixon pitched his tumbler of Scotch forward in shock at his Fifth Avenue town house.
Clif White loved Ronald Reagan, and Clif White had a plan. He had broken the Republican Establishment once. He was convinced he could do it again.
To win at a nominating convention, a candidate needed a majority of delegate votes. Failing that, a second roll call was taken— then a third, and so on. Nixon had won first-ballot commitments from Republicans of every stripe by reminding them of the pain of the 1964 blowout. But with a range of commitments that broad, none could be very deep. A grassroots insurgency to persuade some small number of conservatives, Southerners especially, to vote their consciences for Reagan, just enough to deny Nixon his 50 percent plus one on the first ballot, could blow the whole thing open.
Nelson Rockefeller, waving around Nixon-can’t-win polls he had commissioned using his bottomless financial resources, would be attempting the same thing. Up to the taking of that first convention ballot, their interests were identical— stop Nixon. On the second ballot, White was convinced, Rocky would be overwhelmed. And Reagan would be the Republican nominee."[5]
[5] Ibid, p 282.